... The age distribution of water from a public‐supply well in a deep alluvial aquifer was estimated and used to help explain arsenic variability in the water. The age distribution was computed using a ternary mixing model that combines three lumped parameter models of advection‐dispersion transport of environmental tracers, which represent relatively recent recharge (post‐1950s) containing volatile o ...

... A natural consequence of groundwater withdrawals is the removal of water from subsurface storage, but the overall rates and magnitude of groundwater depletion and capture relative to groundwater withdrawals (extraction or pumpage) have not previously been well characterized. This study assesses the partitioning of long‐term cumulative withdrawal volumes into fractions derived from storage depletio ...

... We apply fluid‐replacement logging in arsenic‐contaminated regions of Bangladesh using a low‐cost, down‐well fluid conductivity logging tool to detect leaks in the cased section of wells. The fluid‐conductivity tool is designed for the developing world: it is lightweight and easily transportable, operable by one person, and can be built for minimal cost. The fluid‐replacement test identifies leaki ...

... This study assesses and characterizes the vulnerability of unregulated groundwater systems to microbial contamination in 18 counties in the state of Georgia using a contamination risk screening strategy based on watershed characteristics and elements of the Safe Drinking Water Act's Wellhead Protection program. Environmental data sources analyzed include septic systems, elevation, land use and lan ...

... Diagnostic derivative interpretation of drawdown data from pumping tests is discussed in this paper. An emphasis is placed on the conceptualization of derivative term of dlgs/dlgt. Use of a combined plot of dlgs/dlgt and ds/dlgt is made to identify various flow patterns from variable discharge tests with infinite conditions, constant rate tests in bounded aquifers, and tests involving double poros ...

... To analyze the effect of filter pack arrangement on the hydraulic properties and the well efficiency of a well design, a step drawdown was conducted in a sand‐filled tank model. Prior to the test, a single filter pack (SFP), granule only, and two dual filter packs (DFPs), type A (granule‐pebble) and type B (pebble‐granule), were designed to surround the well screen. The hydraulic properties and we ...

... Groundwater pumping induces changes in the hydrodynamics of aquifer systems. Rapid urbanization and pumping‐induced changes in local groundwater flow can change the natural heat and chemical balances of an aquifer. In the Nagaoka Plain, Japan, groundwater is being extracted at 145 × 10⁶ m³/year from a highly permeable aquifer consisting of coarse‐grained sediments of Late Pleistocene to Holocene a ...

... Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public‐supply wells are not thoroughly understood. Analysis of historical water‐quality samples from public‐supply wells completed in deep basin‐fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates th ...

... Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water‐quality impairment. Two karst aquifers, the Edwards aquifer in south‐central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public‐supply wells (PSWs). The geochemis ...

... Treated wastewater discharged from more than 400 onsite wastewater treatment systems (OWTS) near the Civic Center area of Malibu, California, 40 km west of downtown Los Angeles, composes 28% of the recharge to a 3.4 km² alluvial aquifer. On the basis of δ¹⁸O and δD data, the fraction of wastewater in some samples was >70%. Ammonium and nitrate concentrations in water from 15 water‐table wells samp ...

... Inherently, confined animal farming operations (CAFOs) and other intense fecal‐rich environments are potential sources of groundwater contamination by enteric pathogens. The ubiquity of microbial matter poses unique technical challenges in addition to economic constraints when sampling wells in such environments. In this paper, we evaluate a groundwater sampling protocol that relies on extended pu ...

... The vulnerability of public supply wells to chlorinated ethene (CE) contamination in part depends on the availability of naturally occurring organic carbon to consume dissolved oxygen (DO) and initiate reductive dechlorination. This was quantified by building a mass balance model of the Kirkwood‐Cohansey aquifer, which is widely used for public water supply in New Jersey. This model was built by t ...

... Multidepth pumping tests (MDPTs), in which different sections of a screen are pumped in sequence, are not being used by hydrogeologists, despite the capability of such tests to resolve uncertainties in the estimation of aquifer characteristics. MDPTs can be used to discern the effects of partial penetration and vertical anisotropy. This article demonstrates the use of MDPTs for a deep and vertical ...

... Wellhead‐protection zones are commonly delineated on the basis of advective travel‐time analysis without considering any aspects of model uncertainty. In the past decade, research efforts have produced quantifiable risk‐based safety margins for protection zones. These margins are based on well‐vulnerability criteria (e.g., travel times, exposure times, peak concentrations) and take model and param ...

... The national occurrence of 83 pesticide compounds in groundwater of the United States and decadal‐scale changes in concentrations for 35 compounds were assessed for the 20‐year period from 1993–2011. Samples were collected from 1271 wells in 58 nationally distributed well networks. Networks consisted of shallow (mostly monitoring) wells in agricultural and urban land‐use areas and deeper (mostly d ...

... Models need not be complex to be useful. An existing groundwater‐flow model of Salt Lake Valley, Utah, was adapted for use with convolution‐based advective particle tracking to explain broad spatial trends in dissolved solids. This model supports the hypothesis that water produced from wells is increasingly younger with higher proportions of surface sources as pumping changes in the basin over tim ...

... Public‐supply wells with long screens in alluvial aquifers can produce waters of differing quality from different depths. Seasonal changes in quality are linked to seasonal changes in pumping rates that influence the distribution of flow into the well screens under pumping conditions and the magnitude and direction of intraborehole flow within the wells under ambient conditions. Groundwater flow a ...

... Groundwater is a vital resource in California, and the concept of “sustainable yield” is an attempt to determine a metric that can ensure the long‐term resilience of groundwater systems. However, its meaning is ambiguous and quantification is challenging. To provide insight into developing a working definition that encompasses the inherent uncertainty and complexity of the term, this paper examine ...